Pharmacological characterization of the chemokine receptor, CCR5

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Abstract
1. We investigated the effects of a number of naturally occurring chemokines (MIP-1alpha, MIP-1beta, RANTES, MCP-2, MCP-3, MCP-4) on different processes linked to the chemokine receptor CCR5 in recombinant CHO cells expressing the receptor at different levels. 2. Internalization of CCR5 following chemokine treatment was studied and MIP-1alpha, MIP-1beta and RANTES (50 nM) were able to induce internalization (similar50%) of the receptor. Internalization due to MCP-2, MCP-3 and MCP-4 was less (similar20%). 3. Phosphorylation of CCR5 following chemokine treatment was studied and MIP-1alpha, MIP-1beta and RANTES (50 nM) were able to induce phosphorylation of CCR5 whereas the other chemokines did not induce CCR5 phosphorylation. 4. MIP-1alpha, MIP-1beta, RANTES and MCP-2 were able to stimulate [(35)S]-GTPgammaS binding, an index of receptor/G protein activation, whereas MCP-3 and MCP-4 had no effect in this assay. MCP-2 was a partial agonist (similar80%) compared to MIP-1alpha, MIP-1beta and RANTES, which gave similar maximal stimulations in this assay. 5. MIP-1alpha, MIP-1beta, RANTES, MCP-2 and MCP-4 were able to stimulate increases in intracellular calcium ions via activation of CCR5 whereas MCP-3 was without effect. 6. It is concluded that different chemokines interacting with CCR5 mediate different patterns of cellular responses.